A lash adjuster used in a valve system of an engine functions on one hand as a fulcrum of a rocker arm bearing thereon an engine valve and on the other hand as a mechanism for automatically adjusting a clearance of the valve (or valve clearance). A hydraulic lash adjuster has a housing in the form of a generally bottomed cylinder and a plunger moveably supported by the housing. The plunger can extend/contract in response to a force exerted by the rocker arm to automatically adjust the valve clearance.
It should be noted here that the plunger and the housing must be temporarily secured by means of some dropout preventing mechanism before they are mounted on an engine in order to prevent the plunger from dropping out of the housing during transportation.
Patent Document 1 cited below discloses a hydraulic lash adjuster in paragraph [0043] and in FIGS. 1 and 5, in which a housing (or body of the adjuster) is provided with an inner circumferential stepped-recess formed in one leading end section of the housing, a plunger formed with an outer circumferential stepped-recess, and a metal retainer (in the form of a ring 24d) with one end thereof abutting against the inner circumferential recess and the other end caulked in the outer circumferential recess to thereby prevent the plunger from coming off the housing.[0043] and in FIGS. 1 and 5, in which a housing (or body of the adjuster) is provided with an inner circumferential stepped-recess formed in one leading end section of the housing, a plunger formed with an outer circumferential stepped-recess, and a plunger-retaining metal ring 24d with one end thereof abutting against the inner circumferential recess and the other end caulked in the outer circumferential recess to thereby prevent the plunger from coming off the housing.